西昆仑山前晚新生代构造活动与青藏高原西北缘的隆升

西昆仑山前晚新生代地貌与沉积特征记录了西昆仑山及青藏高原西北缘的隆升过程。利用沉积学、地貌学、古地磁研究结果,对西昆仑晚新生代构造活动进行了探讨。约25Ma,西昆仑山前沉积面貌发生显著变化,反映西昆仑山整体开始隆升;约5Ma时,西昆仑山前磨拉石发育,表明西昆仑山开始快速隆升。古地磁结果表明:始新世—中新世西昆仑有显著的旋转运动,而第四纪以来水平挤压造成的垂直运动为主,没有明显的旋转运动。河流阶地发育显示,西昆仑地区约在1.2Ma时河流下切开始形成阶地,第四纪中晚期以来西昆仑地区构造抬升幅度与频率加快,全新世中期(约5kaB.P.)有一次快速隆升过程。

Late Cenozoic tectonic movement in the front of the West Kunlun Mountains and uplift of the northwestern margin of the Qinghai-Tibetan Plateau

The Late Cenozoic geomorphologic and sedimentary features in the West Kunlun Mountain front record the uplift process of the West Kunlun Mountains and the western margin of the Qinghai-Tibet Plateau. Based on geomorphologic and paleomagnetic studies, the Late Cenozoic tectonic movement in the West Kunlun are discussed. At about 25 Ma, significant change took place in sedimentary features in the West Kunlun Mountain front, reflecting that the West Kunlun began to be uplifted, and at about 5 Ma, molasse developed in the West Kunlun Mountain front, indicating that the West Kunlun began to be uplifted rapidly. Paleomagnetic results show that marked clockwise rotational movements occurred in the Eocene-Miocene, while vertical movements resulting from horizontal compression have predominated in the Quaternary and no marked rotational movement during this period. The downward incision of the rivers in the West Kunlun at about 1.2 Ma gave rise to terraces. Since the Mid-late Quaternary, the magnitude and frequency of the tectonic uplift have increased, and a rapid tectonic uplift event took place in the middle Holocene (at about 5 ka).